MadHollywood.com

It looks like Lindsay Lohan is about to be a big sister once again.

There's going to be a bundle of joy joining the Lohan family, but it is not mom Dina or sister Ali who is pregnant.

It's her father Michael Lohan and his on-again, off-again girlfriend Kate Major!

Sources confirmed that former "Star" magazine reporter Kate Major is in her first trimester and is expecting a child with LiLo's father, Michael Lohan.

The expectant parents, who were once engaged, have a rocky history that will now be forever linked.

Sources also say that Michael Lohan hasn't told Lindsay or his other children about their soon to be new brother or sister, but we're guessing LiLo's aware of this news by now...so...congrats Lindsay!

Lindsay Lohan, 26, has three other siblings: Michael, 25, Ali, 18, and Cody, 16.